This invention relates to a magnetic-field thermal treatment apparatus adapted to thermally treat an object member, which is placed in a depressurized chamber, especially, a vacuum chamber, as a magnetic field is applied to the object member.
The known magnetic-field thermal treatment apparatuses of this kind include a treatment apparatus for manufacturing, for example, magnetic resistance effect type heads. Recently, a read head called a giant magnetic resistance effect head (GMR head) has been proposed, and such a read head manufacturing thermal treatment apparatus as mentioned above has been provided since it is necessary in the read head manufacturing process to thermally treat a material for the read head as a magnetic field is applied thereto. A method of manufacturing giant magnetic resistance effect heads is disclosed in, for example, Japanese Patent Laid-Open (JP-A) No. 222815/1998.
A related art magnetic-field thermal treatment apparatus used for such a method of manufacturing giant magnetic resistance heads uses a regular electromagnet unit as a magnetic field generating unit. When an electromagnet unit is used for this purpose, the dimensions thereof have to be very large so as to obtain a required magnetic field. When a large electromagnet unit is used, the weight of a magnetic-field thermal treatment apparatus becomes very large. In such a case, it is necessary to secure a load resistance of a floor on which the magnetic-field thermal treatment apparatus is set, and this causes the expense of cost on a building for housing the apparatus to increase, and a place in which the apparatus is installed to be limited. Since a regular electromagnet unit has a large electric power consumption and generates a large quantity of heat, the quantity of water supplied to a cooling system becomes large to cause the running cost to increase. Moreover, in a regular electromagnet unit, there is a limit (1.5 T at the highest) to a generated magnetic field intensity. The results of recent researches into the techniques relating to such an apparatus have made it clear that applying a large magnetic field is effective in improving and stabilizing a magnetic resistance effect of a giant magnetic resistance effect head.
The weight of a body of a magnetic-field thermal treatment apparatus (effective thermal treatment range: diameter xcfx86=152 mm, length=100 mm, magnetic field intensity=1.5 T) using a related art electromagnet unit is about 7000 kg. It is said that the power source capacity and the quantity of cooling water of necessity are 200 V, 190 kVA and 100 liter/min, respectively.
The present invention has been made in view of the above-mentioned circumstances, and provides a magnetic-field thermal treatment apparatus capable of attaining the reduction of the weight thereof.
The present invention also provides a magnetic-field thermal treatment apparatus capable of attaining the reduction of consumption of utilities, such as electric power and cooling water.
The present invention further provides a magnetic-field thermal treatment apparatus capable of attaining an increase in the generated magnetic field intensity.
The present invention is applied to a magnetic-field thermal treatment apparatus adapted to carry out a thermal treatment for an object member, which is placed in a depressurized chamber, as a magnetic field is applied to the member. The magnetic-field thermal treatment apparatus according to the present invention is characterized in that a heater is provided around the chamber with a superconductive magnet unit provided as a magnetic field generating unit.
According to an aspect of the present invention, the magnetic-field thermal treatment apparatus holds in a depressurized chamber object members formed of plural sheets of substrate-like members held in a substrate holder and retained in the chamber so that the surfaces of the substrate-like members become horizontal. The superconductive magnet unit has at least a pair of superconductive coils provided in a vertically opposed state with the chamber positioned therebetween, so as to exert a magnetic field, which is parallel to the surfaces of the object substrate-like members, on the same object substrate-like members.
According to another aspect of the present invention, the magnetic-field thermal treatment apparatus holds in a depressurized chamber object members formed of plural sheets of substrate-like members held in a substrate holder and retained in the chamber so that the surfaces of the substrate-like members become parallel to one another in the lateral direction. The superconductive magnet unit has at least one superconductive coil surrounding the chamber horizontally, so as to exert a magnetic field, which is parallel to the surfaces of the object substrate-like members, on the same object substrate-like members.